• Title/Summary/Keyword: 대류권

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Effect of Tropospheric Delay Irregularity in Network RTK Environment (기준국 간 대류권 지연 변칙이 네트워크 RTK에 미치는 영향)

  • Han, Younghoon;Ko, Jaeyoung;Shin, Mi-Young;Cho, Deuk-Jae
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.19 no.11
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    • pp.2569-2575
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    • 2015
  • Network RTK generally uses a linear interpolation method by using the corrections from reference stations. This minimizes the spatial decorrelation error caused by the increase of distance between the reference station's baseline and user's baseline. However, tropospheric delay, a function of the meteorological data can cause a spatial decorrelation characteristic among reference stations within a network by local meteorological difference. A non-linear characteristic of tropospheric delay can deteriorate Network RTK performance. In this paper, the modeling of tropospheric delay irregularity is made from the data when the typhoon is occurred. By using this modeling, analyzing the effect of meteorological difference between reference stations on correction is performed. Finally, we analyze an effect of non-linear characteristics of tropospheric delay among reference stations to Network RTK user.

Effects of the El Niño on Tropospheric Ozone in a Simulation using a Climate-Chemistry Model (기후-대기화학모델이 모의한 엘니뇨가 대류권 오존에 미치는 영향)

  • Moon, Byung-Kwon;Yeh, Sang-Wook;Park, Rokjin J.;Song, Chang-Keun;Youn, Daeok
    • Journal of the Korean earth science society
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    • v.34 no.7
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    • pp.662-668
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    • 2013
  • We examine the effects of El Ni$\tilde{n}$o on tropospheric ozone through the simulation of a Climate-Chemistry model for a 40-year period (1971-2010). The Empirical Orthogonal Function (EOF) analysis reveals that the tropospheric ozone concentration in the central-eastern Pacific decreases when the El Ni$\tilde{n}$o occurs, which is consistent with the observation. However, the increase of ozone over Indian Ocean-Indonesia regions is weak in the simulation compared to the observations. We analyze details of the 2006 El Ni$\tilde{n}$o event to understand the mechanism that caused the change of ozone due to El Ni$\tilde{n}$o. It is found that enhanced convection as well as higher water vapor followed by shortened lifetime has led to lower the tropospheric ozone. Downward motion induced by the changes of atmospheric circulation due to sea surface temperature forcing, together with the decrease of water vapor, has brought ozone produced in the upper troposphere over the Indian Ocean.

ESTIMATION OF PRECIPITABLE WATER VAPOR USING THE GPS (GPS를 이용한 대류권의 수증기량 측정)

  • 문용진;최규홍;박필호
    • Journal of Astronomy and Space Sciences
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    • v.16 no.1
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    • pp.61-68
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    • 1999
  • The radio waves transmitted from GPS satellites is delayed by the troposphere as they propagate to Earth-based GPS receivers. The troposphere delay is usually divided into two parts, the dry delay due to the atmospheric gases and the wet delay due to the water vapor. In this study for the month of May in 1998 the GPS data from two stations(Taejon, Suwon) were used to estimate the total troposphere delay in the zenith direction by the least square method. The dry delay in the zenith direction can be evaluated by using surface pressure values at the station, then the zenith wet delay is obtained by removing the zenith dry delay from the total delay. The zenith wet delay is strongly correlated with the total precipitable water. The quality of the estimate has been assessed by comparison with radiosonde data at Osan. We found the food agreement in precipitable water of the GPS estimates and the radiosonde data. The standard deviation of the difference of the difference between the GPS and radiosonde observations was 3.68mm at Suwon.

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The Analysis of Performance of Precise Single Positioning according to estimation accuracy of Satellite Clock Error (위성 클럭 에러 추정 정확도에 따른 정밀 단독 측위 성능 분석)

  • Zhang, Yu;Shin, Yun-Ho;Shin, Hyun-Sik
    • The Journal of the Korea institute of electronic communication sciences
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    • v.7 no.2
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    • pp.327-332
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    • 2012
  • In this paper, we analyzed the influence of different observation stations distributions on satellite clock offset estimation based on the PANDA software. The result shows that, when the distance between stations is shorter than 200km, the correlation of troposphere parameter and satellite clock offset parameter is strong, the accuracy of satellite clock offset estimation will be up to 0.8ns; when the distance between stations is up to 500km, as the correction of troposphere parameter and satellite clock offset parameter is significantly reduced, and the two kinds of parameters can be distinguished.

Feasibility Study for Derivation of Tropospheric Ozone Motion Vector Using Geostationary Environmental Satellite Measurements (정지궤도 위성 대류권 오존 관측 자료를 이용한 대류권 이동벡터 산출 가능성 연구)

  • Shin, Daegeun;Kim, Somyoung;Bak, Juseon;Baek, Kanghyun;Hong, Sungjae;Kim, Jaehwan
    • Korean Journal of Remote Sensing
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    • v.38 no.6_1
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    • pp.1069-1080
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    • 2022
  • The tropospheric ozone is a pollutant that causes a great deal of damage to humans and ecosystems worldwide. In the event that ozone moves downwind from its source, a localized problem becomes a regional and global problem. To enhance ozone monitoring efficiency, geostationary satellites with continuous diurnal observations have been developed. The objective of this study is to derive the Tropospheric Ozone Movement Vector (TOMV) by employing continuous observations of tropospheric ozone from geostationary satellites for the first time in the world. In the absence of Geostationary Environmental Monitoring Satellite (GEMS) tropospheric ozone observation data, the GEOS-Chem model calculated values were used as synthetic data. Comparing TOMV with GEOS-Chem, the TOMV algorithm overestimated wind speed, but it correctly calculated wind direction represented by pollution movement. The ozone influx can also be calculated using the calculated ozone movement speed and direction multiplied by the observed ozone concentration. As an alternative to a backward trajectory method, this approach will provide better forecasting and analysis by monitoring tropospheric ozone inflow characteristics on a continuous basis. However, if the boundary of the ozone distribution is unclear, motion detection may not be accurate. In spite of this, the TOMV method may prove useful for monitoring and forecasting pollution based on geostationary environmental satellites in the future.

Impact of Tropospheric Modeling Schemes into Accuracy of Estimated Ellipsoidal Heights by GPS Baseline Processing: Experimental Analysis and Results (GPS 기선해석에 의한 타원체고 추정에서 대류권 오차 보정기법이 정확도에 미치는 영향에 관한 실험적 분석)

  • Lee, Hungkyu
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.36 no.4
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    • pp.245-254
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    • 2018
  • Impact of tropospheric correction techniques on accuracy of the GPS (Global Positioning System) derived ellipsoidal heights has been experimentally assessed in this paper. To this end, 247 baselines were constructed from a total of 88 CORS (Continuously Operating Reference Stations) in Korea. The GPS measurements for seven days, acquired from the so-called integrated GNSS (Global Navigation Satellite Systems) data center via internet connection, have been processed by two baseline processing software packages with an application of the empirical models, such as Hopfield, modified Hopfield and Saastamoinen, and the estimation techniques based on the DD (Double-Differenced) measurements and the PPP (Precise Point Positioning) technique; hence a total number of the baseline processed and tested was 8,645. Accuracy and precision of the estimated heights from the various correction schemes were analyzed about baseline lengths and height differences of the testing baselines. Details of these results are summarized with a view to hopefully providing an overall guideline of a suitable selection of the modeling scheme with respect to processing conditions, such as the baseline length and the height differences.

Intercomparison of Middle and Low Tropospheric Temperature from Satellite with ECMWF Reanalyses; Temporal and Spatial Variability (위성관측에서 유도된 중간 및 하부 대류권 온도와 ECMWF 재분석 결과 사이의 상호 비교; 시.공간 변동)

  • 이은주;유정문
    • Proceedings of the KSRS Conference
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    • 2000.04a
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    • pp.43-48
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    • 2000
  • 중간 및 하부 대규권의 열적 상태에 대한 결과들의 상대적인 정확성을 평가하기 위하여 대기대순환 모델의 재분석(1980-93년) 그리고 세 종류의 위성관측 자료들(1980-97년)을 태평양, 한반도 부근에 대한 시.공간 분석으로 상호 비교하였다. 중간 대류권 온도를 반영하는 위성자료는 본 연구에서 유도된 Microwave Sounding Unit (MSU) 채널2 직하점 밝기온도(MSU2)와 Spencer and Christy(1992a)가 전체 주사자료를 사용하여 유도된 채널2 밝기 온도(SC2)이고, 하부 대류권 온도를 반영하는 위성자료는 Spencer and Christy(1992a)가 유도한 것이다(SC2R). 또한, 모델 자료는 ECMWF 재분석 온도이며, 위성관측 자료와의 비교를 위하여 재구성되었다. 한편, 각 위.경도 격자에서 위성관측과 모델 재분석의 월평균 값들의 상관도 전구적으로 조사하였다. 세 종류의 관측 자료들 간의 상관은 중.고위도에서 높았으나(r$\geq$0.9), 저위도 그리고 대류가 활발한 열대 서태평양 및 콩고강 부근에서 낮았다(r~0.65). 특히 SC2R에 대한 다른 자료의 상관이 상대적으로 낮았다. 이는 하부 대류권의 열적 상태를 반영하는 SC2R이 수적 및 지표방출의 영향으로 잡음을 크게 내포하기 때문인 것으로 추정되었다. 관측들과 모델 온도에 대한 월평균과 아노말리 값의 분석에서 시.공간 변동은 대체로 유사하였다. 관측 및 모델 자료는 열대 태평양 이외의 지역에 대한 월평균 값 모드1에서 연주기를 보였으나, 열대 태평양의 경우 모드2에서 보였다. 열대 태평양의 MSU2 모드1은 Walker 순환에 의한 동.서 대비를 보인 반면, 다른 위성관측과 모델 자료에서는 이러한 형태가 현저하지 않았다. 이 지역의 아노말리 값 모드2에서 위성관측들은 엘리뇨 기간에 적도를 중심으로 열대 동태평양 부근에서 아령모양의 대칭 형태를 보였으나 모델 결과에서는 이러한 특징이 약하였다. 관측과 모델 모두는 열대 태평양에 대한 아노말리 값의 모드 1,2에서 엘니뇨와 라니냐에 의한 경년변동을 뚜렷하게 보였다.

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